This invention relates to a process for synthesizing fluorocarbon halides. In a more particular manner, this invention concerns itself with a novel route for effecting the synthesis of fluorocarbon halides using halogen fluorosulfates as a reaction component.
Perfluorohalides are well known for their utility as intermediate precursors for a wide variety of synthetic reactions. At the present time there is no simple and convenient process for producing these compounds. One of the better known processes is that referred to as the Hunsdiecker reaction which is disclosed in M. Hudlicky, Chemistry of Organic Fluorine Compounds, 2nd Ed., Halsted Press, 225 (1976). In this reaction, the preparation of perfluorocarbon halides from fluorocarbon acids or their derivatives via decarboxylation requires the formation of the silver salt of the fluorocarbon acid. Since silver is required, the process is expensive . Also, the silver salt must then be vigorously dried prior to a reaction with an elemental halogen, such as chlorine, bromine or iodine, at elevated temperatures. The Hunsdiecker reaction is illustrated by the following equation. EQU R.sub.f CO.sub.2 Ag+X.sub.2.sup..DELTA. R.sub.f X+AgX+CO.sub.2 ( 1)
wherein R.sub.f is a perfluoroalkyl radical and X is chlorine, bromine or iodine.
With the present invention, however, a novel, inexpensive, simple and efficient method has been found which utilizes halogen fluorosulfate having the general formula EQU XSO.sub.3 F (2)
wherein X is chlorine, bromine or iodine. The method of this invention eliminates the need for heating. Also, it permits the use of both the inexpensive fluorocarbon acids and their inexpensive alkali metal salts as a coreactant, thus avoiding the requirement for the costly silver salts. The reaction between the fluorosulfate and the fluorocarbon acid takes place at ambient temperatures with a reaction temperature of from about 0.degree. C. to 50.degree. C. being preferred.